Many, if not most, glass containers, including a wide variety of bottles and jars, are, and for many years have been, manufactured by machines of the I.S. type, a type that uses a multiplicity of side-by-side sections each of which forms containers in a two-step molding operation. In a glass container forming operation of this type, a preform of the container, often called a parison or a blank, is formed in a first mold at a blank molding station of the I.S. machine section, either by pressing or blowing, and the blank is then transferred by a 180.degree. inverting operation in a vertical plane to a second mold of the I.S. machine section, often called a blow mold, for forming into the finished container by blowing. In modern I.S. machines typically a multiplicity of containers, such as two or three or even four containers, are simultaneously formed at each section of the I.S. machine, and such machines typically incorporate a rather large number of sections, such as six or eight or even ten sections. U.S. Pat. No. 4,427,431 (Mumford et al.), which is assigned to the assignee of this application, the disclosure of which is incorporated by reference herein, generally discloses a glass container forming machine of this general type.
Containers leaving the blow molds of an I.S. machine are quite hot and need to be cooled to an appreciable extent before they can be subjected to the kinds of mechanical handling steps and devices that are necessary to transfer such containers to an annealing lehr for heat treatment to relieve excess residual internal stresses that can result from the forming steps. Thus, a typical I.S. machine is provided with an air cooled dead plate to which containers are transferred from the blow molds of an I.S. machine by take-out tong mechanisms that are a part of the I.S. machine. The containers are permitted to dwell on the dead plate for a period of time, during which they partially cool to a temperature at which they will be capable of undergoing further handling. Thereupon, the containers are transferred to a moving conveyor, often called a machine conveyor, an action that requires a 90.degree. turning movement of the containers by a sweepout head. The transfer of containers from I.S. machine blow molds to dead plates and from dead plates to a machine conveyor by sweepout heads is generally described in the aforesaid U.S. Pat. No. 4,427,431 and also in U.S. Pat. No. 4,162,911 (Mallory) and U.S. Pat. No. 4,222,480 (Perry), each of which is also assigned to the assignee of this application, the disclosure of each of which is also incorporated by reference herein.
Containers from an I.S. machine that are being conveyed away from the I.S. machine by the machine conveyor are transferred to another conveyor, usually called a cross-conveyor, which extends perpendicular to the machine conveyor and presents the containers at the inlet to an annealing lehr. A container transfer device is provided to effect the transfer of containers from the machine conveyor to the cross-conveyor. This arrangement is generally shown in U.S. Pat. No. 4,193,784 (Mumford), which is also assigned to the assignee of this application, the disclosure of which is also incorporated by reference herein. In practice, transfer devices performing the function of the transfer device of the aforesaid U.S. Pat. No. 4,193,784 are often constructed in an arcuate or crescent-shape configuration. Containers on the cross-conveyor at the inlet to an annealing lehr are thereupon transferred in groups of a multiplicity of containers in each group to a moving conveyor of the lehr by a transfer device that is often called a lehr loader or stacker. U.S. Pat. No. 4,290,517 (Hafferkamp), which is also assigned to the assignee of this application, the disclosure of which is also incorporated by reference herein, discloses a prior art lehr loader for transferring containers on a cross-conveyor to the conveyor of an annealing lehr in the manner described above.
The many container handling steps and devices involved in transferring containers from I.S. machine dead plates to an annealing lehr conveyor, as described, must be carefully controlled with respect to one another, both as to the speeds of such handling steps and their timing with respect to one another. Further, I.S. machines, as described, are used to produce containers of different designs and sizes, and each job change on an I.S. machine often requires changes in the system for controlling the operation of the container handling devices, frequently involving changes in the spacing between containers on the machine conveyor and the cross-conveyor. Heretofore, such I.S. machine job changes involved changing the gearbox and/or the sprocket ratios of the drives used to drive the machine conveyor, the cross-conveyor and the chain transfer device for transferring containers from the machine conveyor to the cross-conveyor. Of course, such changes lead to significant downtime in the operation of an I.S. machine, which reduces the overall productivity of the machine. Moreover, even in steady state operation, variables can occur in the operation of container handling devices, as described, do, for example, to stretch occurring in the conveyor belts used in some of such devices.